JoAnn's was less expensive than the paper I wanted (and it will be easier to remove if I move.) To get a nice straight edge at the top, I used a 1/2 inch strip of cardboard (find it in upholstery shops.) The top edge of fabric is right side to the wall and the cardboard runs along the wall/ceiling edge on the wrong side of fabric. I stapled through the cardboard and fabric to the wall and the fabric comes over the top of that so the staples are hidden. The sides and bottom are just turned under and stapled. I may get decorative tacks to cover the staples, but I only used a few and they are not noticeable.
The keyboard tray is from Office Depot. You need about a 33" opening to install it according to the instructions. My opening is 30" Just contact me if you have a similar situation and I can tell you how we made it work. I love it!
The shelves are from Lowes. You need to cut "x's" in the fabric for installing anchors for the shelf brackets. Move the fabric away from the anchor area to keep your drill from catching on a thread and eating the fabric. (I have no experience with that whatsoever - just guessing that might happen...)
The crate that elevates the printer to give me another storage nook is from Michaels. I will paint it to match the shelves (in my dreams.)
The chair slipcover is from my easy pattern you can find on Craftsy.